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use std::ops::Deref;
use crate::{
archetype::Archetype,
change_detection::MutUntyped,
component::ComponentId,
entity::Entity,
event::{Event, EventId, Events, SendBatchIds},
observer::{Observers, TriggerTargets},
prelude::{Component, QueryState},
query::{QueryData, QueryFilter},
system::{Commands, Query, Resource},
};
use super::{
unsafe_world_cell::{UnsafeEntityCell, UnsafeWorldCell},
EntityMut, Mut, World,
};
/// A [`World`] reference that disallows structural ECS changes.
/// This includes initializing resources, registering components or spawning entities.
pub struct DeferredWorld<'w> {
// SAFETY: Implementors must not use this reference to make structural changes
world: UnsafeWorldCell<'w>,
}
impl<'w> Deref for DeferredWorld<'w> {
type Target = World;
fn deref(&self) -> &Self::Target {
// SAFETY: Structural changes cannot be made through &World
unsafe { self.world.world() }
}
}
impl<'w> UnsafeWorldCell<'w> {
/// Turn self into a [`DeferredWorld`]
///
/// # Safety
/// Caller must ensure there are no outstanding mutable references to world and no
/// outstanding references to the world's command queue, resource or component data
#[inline]
pub unsafe fn into_deferred(self) -> DeferredWorld<'w> {
DeferredWorld { world: self }
}
}
impl<'w> From<&'w mut World> for DeferredWorld<'w> {
fn from(world: &'w mut World) -> DeferredWorld<'w> {
DeferredWorld {
world: world.as_unsafe_world_cell(),
}
}
}
impl<'w> DeferredWorld<'w> {
/// Reborrow self as a new instance of [`DeferredWorld`]
#[inline]
pub fn reborrow(&mut self) -> DeferredWorld {
DeferredWorld { world: self.world }
}
/// Creates a [`Commands`] instance that pushes to the world's command queue
#[inline]
pub fn commands(&mut self) -> Commands {
// SAFETY: &mut self ensure that there are no outstanding accesses to the queue
let command_queue = unsafe { self.world.get_raw_command_queue() };
// SAFETY: command_queue is stored on world and always valid while the world exists
unsafe { Commands::new_raw_from_entities(command_queue, self.world.entities()) }
}
/// Retrieves a mutable reference to the given `entity`'s [`Component`] of the given type.
/// Returns `None` if the `entity` does not have a [`Component`] of the given type.
#[inline]
pub fn get_mut<T: Component>(&mut self, entity: Entity) -> Option<Mut<T>> {
// SAFETY:
// - `as_unsafe_world_cell` is the only thing that is borrowing world
// - `as_unsafe_world_cell` provides mutable permission to everything
// - `&mut self` ensures no other borrows on world data
unsafe { self.world.get_entity(entity)?.get_mut() }
}
/// Retrieves an [`EntityMut`] that exposes read and write operations for the given `entity`.
/// Returns [`None`] if the `entity` does not exist.
/// Instead of unwrapping the value returned from this function, prefer [`Self::entity_mut`].
#[inline]
pub fn get_entity_mut(&mut self, entity: Entity) -> Option<EntityMut> {
let location = self.entities.get(entity)?;
// SAFETY: if the Entity is invalid, the function returns early.
// Additionally, Entities::get(entity) returns the correct EntityLocation if the entity exists.
let entity_cell = UnsafeEntityCell::new(self.as_unsafe_world_cell(), entity, location);
// SAFETY: The UnsafeEntityCell has read access to the entire world.
let entity_ref = unsafe { EntityMut::new(entity_cell) };
Some(entity_ref)
}
/// Retrieves an [`EntityMut`] that exposes read and write operations for the given `entity`.
/// This will panic if the `entity` does not exist. Use [`Self::get_entity_mut`] if you want
/// to check for entity existence instead of implicitly panic-ing.
#[inline]
pub fn entity_mut(&mut self, entity: Entity) -> EntityMut {
#[inline(never)]
#[cold]
fn panic_no_entity(entity: Entity) -> ! {
panic!("Entity {entity:?} does not exist");
}
match self.get_entity_mut(entity) {
Some(entity) => entity,
None => panic_no_entity(entity),
}
}
/// Returns [`Query`] for the given [`QueryState`], which is used to efficiently
/// run queries on the [`World`] by storing and reusing the [`QueryState`].
///
/// # Panics
/// If state is from a different world then self
#[inline]
pub fn query<'s, D: QueryData, F: QueryFilter>(
&'w mut self,
state: &'s mut QueryState<D, F>,
) -> Query<'w, 's, D, F> {
state.validate_world(self.world.id());
state.update_archetypes(self);
// SAFETY: We ran validate_world to ensure our state matches
unsafe {
let world_cell = self.world;
Query::new(
world_cell,
state,
world_cell.last_change_tick(),
world_cell.change_tick(),
)
}
}
/// Gets a mutable reference to the resource of the given type
///
/// # Panics
///
/// Panics if the resource does not exist.
/// Use [`get_resource_mut`](DeferredWorld::get_resource_mut) instead if you want to handle this case.
#[inline]
#[track_caller]
pub fn resource_mut<R: Resource>(&mut self) -> Mut<'_, R> {
match self.get_resource_mut() {
Some(x) => x,
None => panic!(
"Requested resource {} does not exist in the `World`.
Did you forget to add it using `app.insert_resource` / `app.init_resource`?
Resources are also implicitly added via `app.add_event`,
and can be added by plugins.",
std::any::type_name::<R>()
),
}
}
/// Gets a mutable reference to the resource of the given type if it exists
#[inline]
pub fn get_resource_mut<R: Resource>(&mut self) -> Option<Mut<'_, R>> {
// SAFETY: &mut self ensure that there are no outstanding accesses to the resource
unsafe { self.world.get_resource_mut() }
}
/// Gets a mutable reference to the non-send resource of the given type, if it exists.
///
/// # Panics
///
/// Panics if the resource does not exist.
/// Use [`get_non_send_resource_mut`](World::get_non_send_resource_mut) instead if you want to handle this case.
///
/// This function will panic if it isn't called from the same thread that the resource was inserted from.
#[inline]
#[track_caller]
pub fn non_send_resource_mut<R: 'static>(&mut self) -> Mut<'_, R> {
match self.get_non_send_resource_mut() {
Some(x) => x,
None => panic!(
"Requested non-send resource {} does not exist in the `World`.
Did you forget to add it using `app.insert_non_send_resource` / `app.init_non_send_resource`?
Non-send resources can also be added by plugins.",
std::any::type_name::<R>()
),
}
}
/// Gets a mutable reference to the non-send resource of the given type, if it exists.
/// Otherwise returns `None`.
///
/// # Panics
/// This function will panic if it isn't called from the same thread that the resource was inserted from.
#[inline]
pub fn get_non_send_resource_mut<R: 'static>(&mut self) -> Option<Mut<'_, R>> {
// SAFETY: &mut self ensure that there are no outstanding accesses to the resource
unsafe { self.world.get_non_send_resource_mut() }
}
/// Sends an [`Event`].
/// This method returns the [ID](`EventId`) of the sent `event`,
/// or [`None`] if the `event` could not be sent.
#[inline]
pub fn send_event<E: Event>(&mut self, event: E) -> Option<EventId<E>> {
self.send_event_batch(std::iter::once(event))?.next()
}
/// Sends the default value of the [`Event`] of type `E`.
/// This method returns the [ID](`EventId`) of the sent `event`,
/// or [`None`] if the `event` could not be sent.
#[inline]
pub fn send_event_default<E: Event + Default>(&mut self) -> Option<EventId<E>> {
self.send_event(E::default())
}
/// Sends a batch of [`Event`]s from an iterator.
/// This method returns the [IDs](`EventId`) of the sent `events`,
/// or [`None`] if the `event` could not be sent.
#[inline]
pub fn send_event_batch<E: Event>(
&mut self,
events: impl IntoIterator<Item = E>,
) -> Option<SendBatchIds<E>> {
let Some(mut events_resource) = self.get_resource_mut::<Events<E>>() else {
bevy_utils::tracing::error!(
"Unable to send event `{}`\n\tEvent must be added to the app with `add_event()`\n\thttps://docs.rs/bevy/*/bevy/app/struct.App.html#method.add_event ",
std::any::type_name::<E>()
);
return None;
};
Some(events_resource.send_batch(events))
}
/// Gets a pointer to the resource with the id [`ComponentId`] if it exists.
/// The returned pointer may be used to modify the resource, as long as the mutable borrow
/// of the [`World`] is still valid.
///
/// **You should prefer to use the typed API [`World::get_resource_mut`] where possible and only
/// use this in cases where the actual types are not known at compile time.**
#[inline]
pub fn get_resource_mut_by_id(&mut self, component_id: ComponentId) -> Option<MutUntyped<'_>> {
// SAFETY: &mut self ensure that there are no outstanding accesses to the resource
unsafe { self.world.get_resource_mut_by_id(component_id) }
}
/// Gets a `!Send` resource to the resource with the id [`ComponentId`] if it exists.
/// The returned pointer may be used to modify the resource, as long as the mutable borrow
/// of the [`World`] is still valid.
///
/// **You should prefer to use the typed API [`World::get_resource_mut`] where possible and only
/// use this in cases where the actual types are not known at compile time.**
///
/// # Panics
/// This function will panic if it isn't called from the same thread that the resource was inserted from.
#[inline]
pub fn get_non_send_mut_by_id(&mut self, component_id: ComponentId) -> Option<MutUntyped<'_>> {
// SAFETY: &mut self ensure that there are no outstanding accesses to the resource
unsafe { self.world.get_non_send_resource_mut_by_id(component_id) }
}
/// Retrieves a mutable untyped reference to the given `entity`'s [`Component`] of the given [`ComponentId`].
/// Returns `None` if the `entity` does not have a [`Component`] of the given type.
///
/// **You should prefer to use the typed API [`World::get_mut`] where possible and only
/// use this in cases where the actual types are not known at compile time.**
#[inline]
pub fn get_mut_by_id(
&mut self,
entity: Entity,
component_id: ComponentId,
) -> Option<MutUntyped<'_>> {
// SAFETY: &mut self ensure that there are no outstanding accesses to the resource
unsafe { self.world.get_entity(entity)?.get_mut_by_id(component_id) }
}
/// Triggers all `on_add` hooks for [`ComponentId`] in target.
///
/// # Safety
/// Caller must ensure [`ComponentId`] in target exist in self.
#[inline]
pub(crate) unsafe fn trigger_on_add(
&mut self,
archetype: &Archetype,
entity: Entity,
targets: impl Iterator<Item = ComponentId>,
) {
if archetype.has_add_hook() {
for component_id in targets {
// SAFETY: Caller ensures that these components exist
let hooks = unsafe { self.components().get_info_unchecked(component_id) }.hooks();
if let Some(hook) = hooks.on_add {
hook(DeferredWorld { world: self.world }, entity, component_id);
}
}
}
}
/// Triggers all `on_insert` hooks for [`ComponentId`] in target.
///
/// # Safety
/// Caller must ensure [`ComponentId`] in target exist in self.
#[inline]
pub(crate) unsafe fn trigger_on_insert(
&mut self,
archetype: &Archetype,
entity: Entity,
targets: impl Iterator<Item = ComponentId>,
) {
if archetype.has_insert_hook() {
for component_id in targets {
// SAFETY: Caller ensures that these components exist
let hooks = unsafe { self.components().get_info_unchecked(component_id) }.hooks();
if let Some(hook) = hooks.on_insert {
hook(DeferredWorld { world: self.world }, entity, component_id);
}
}
}
}
/// Triggers all `on_remove` hooks for [`ComponentId`] in target.
///
/// # Safety
/// Caller must ensure [`ComponentId`] in target exist in self.
#[inline]
pub(crate) unsafe fn trigger_on_remove(
&mut self,
archetype: &Archetype,
entity: Entity,
targets: impl Iterator<Item = ComponentId>,
) {
if archetype.has_remove_hook() {
for component_id in targets {
let hooks =
// SAFETY: Caller ensures that these components exist
unsafe { self.world.components().get_info_unchecked(component_id) }.hooks();
if let Some(hook) = hooks.on_remove {
hook(DeferredWorld { world: self.world }, entity, component_id);
}
}
}
}
/// Triggers all event observers for [`ComponentId`] in target.
///
/// # Safety
/// Caller must ensure observers listening for `event` can accept ZST pointers
#[inline]
pub(crate) unsafe fn trigger_observers(
&mut self,
event: ComponentId,
entity: Entity,
components: impl Iterator<Item = ComponentId>,
) {
Observers::invoke(self.reborrow(), event, entity, components, &mut ());
}
/// Triggers all event observers for [`ComponentId`] in target.
///
/// # Safety
/// Caller must ensure `E` is accessible as the type represented by `event`
#[inline]
pub(crate) unsafe fn trigger_observers_with_data<E>(
&mut self,
event: ComponentId,
entity: Entity,
components: impl Iterator<Item = ComponentId>,
data: &mut E,
) {
Observers::invoke(self.reborrow(), event, entity, components, data);
}
/// Sends a "global" [`Trigger`] without any targets.
pub fn trigger<T: Event>(&mut self, trigger: impl Event) {
self.commands().trigger(trigger);
}
/// Sends a [`Trigger`] with the given `targets`.
pub fn trigger_targets(&mut self, trigger: impl Event, targets: impl TriggerTargets) {
self.commands().trigger_targets(trigger, targets);
}
/// Gets an [`UnsafeWorldCell`] containing the underlying world.
///
/// # Safety
/// - must only be used to to make non-structural ECS changes
#[inline]
pub(crate) fn as_unsafe_world_cell(&mut self) -> UnsafeWorldCell {
self.world
}
}